This invention relates to electronic system maintenance trainers and in particular to waveform generating means for electronically simulating the internal functions of the electronic system represented by the maintenance trainer.
Maintenance training comprehends the use of an operational electronic system, such as a radar, or a facsimile of the electronic system, into which an instructor introduces a fault or error (actually, in the case of an operational system, or, electronically in the case of a facsimile). The student then analyses the problem and makes the corrections (such as replacing a particular circuit card) that he thinks are necessary. The system displays, meters and oscilloscope indicate both the original problem and the results of the student's corrective actions.
Maintenance training traditionally has been considered an area that requires the actual equipment (end item). The reasons usually advanced are (a) the "realism" of the equipment, (b) user acceptance, and (c) the availability of such devices. Problems that have been encountered are (a) the end item is costly, (b) the end item is frequently more sophisticated than training needs dictate, and (c) the end item is not specifically designed to be "student proof" for training.
Simulation of end items is a method to reduce the costs of training equipment. The object is to design training equipment which will respond to a student the way the real equipment would insofar as trailing is concerned, but cost less initially and not have the overhead of maintenance and operation of the original equipment. As used herein, maintenance simulation is the application of simulation techniques to the area of maintenance training.
The nature of simulation is applicable to operational training because designers are required only to mimic the outward functions of the original equipment. Of importance today is maintenance simulation which requires mimicing the inner functions of the original equipment.
General purpose computers were used in maintenance simulators as early as the mid-50's. Unfortunately, the costs exceeded the benefits of maintenance simulation because of the dedicated computer requirement. Lately, the price of computers has dropped to the point where maintenance simulation is practical. In view of this, it is apparent that maintenance simulation as an alternative to the use of operational equipment can potentially save large amounts of money when applied to high cost systems, such as radar sets, weapon control systems and power systems. Although electronic maintenance simulation is desirable and has been for some time, lack of capability to cheaply produce circuit waveforms for electronics training (i.e., dynamically-controllable, highspeed complex outputs) has prevented maintenance simulation from achieving widespread use. Industrial system control concepts--using large scale integration (LSI) devices such as: eight bit microprocessors and cheap transistor memory devices--have changed the picture drastically in favor of maintenance simulation. However, effective electronic waveform simulation further requires the implementation of a programmable waveform generator to provide one and two megahertz data display ratio. Such a device is essential because no single commercially available microprocessor can perform such output rates continuously and direct a microcomputer system at the same time. There presently is the need therefore for a self-contained output device slaved to the host microcomputer which gives the microcomputer the ability to output unlimited iterations or arbritrary waveforms. The present invention is directed toward satisfying that need. It is also desirable that a programmable waveform generator of this type be readily adaptable to use with any electronic system maintenance trainer. The present invention also addresses this requirement and provides a device that is not limited in its application to any trainer or type of trainer.